N-alkylimides find many uses in electrics/electronics, medicine, agrochemicals, dyes, pigments and surfactants and thus are being actively studied. And, a variety of imide derivatives including phthalimide, succinimide and maleimide are used in many applications. U.S. Pat. No. 4,596,863 disclosed a use of N-alkylimide copolymers as sizing agent. Recently, U.S. Pat. No. 6,437,009 disclosed a use as low foam wetting agent. The use of imide compounds is expanding from medicinal and electric/electronic industries to more diverse industry fields.
In general, N-alkylimide compounds may be prepared by such known methods as presented in F. Barrow [J. Chem. Soc. (London), p. 638 (1939)], i.e., by condensation of carboxylic acid and primary amine, condensation of carboxylic acid ester and primary amine or condensation of carboxylic acid anhydride and primary amine.
Also, N-alkylimide compounds can be prepared from imide, for example, by the methods presented in U.S. Pat. No. 2,628,963 and U.S. Pat. No. 2,753,356, in which carboxyimide and primary amine are reacted at high temperature and under high pressure.
Polyimides frequently used as electronics material may be prepared by the above method. But, synthetic polyimides are prepared by condensing polyamic acid precursor at high temperature because of difficulty in processing, as disclosed in U.S. Pat. No. 5,290,497.
But, the condensation requires high temperature or high pressure and the primary amine should have a high basicity. Because of these problems, efforts to develop various compounds were unsuccessful. Especially, β-sulfoneamine has to be used as primary amine to prepare β-sulfonimide. But, preparation of β-sulfonimide by the afore-mentioned process is difficult because β-sulfoneamine has a low basicity.